1. Field of the Invention
The present invention relates to erasing heads and more particularly to erasing heads having a sufficiently high erasing effect and able to minimize the distortion ratio for recording.
2. Description of the Prior Art
Various types of erasing heads have been known and used in respect of record and reproduce apparatus. Among them, semi-double gap type erasing heads, in FIG. 1, and double gap type heads, as illustrated in FIG. 2, are most generally used. In FIG. 1, 1a is a ferrite core, 2a is a non-magnetic gap material element, 3 is a magnetic member of high permeability and 4a is a winding. In the structure illustrated in FIG. 2, 1b is a ferrite core, 2b is a nonmagnetic gap material element and 4b is a winding.
So far as the erasing ratio is concerned, these known erasing heads are all satisfactory for practical use except in the case of unsuitably designed ones. However, it has been found that they have a limitation in respect of reduction of the distortion ratio. When new information is recorded after erasing, it is impossible for these known erasing heads to reduce the distortion ratio of the recorded signals up to a desired level below a certain limit.